Latch mechanism



Aug. 10,1965 K. L. vou 3,199,939

LATCH MECHANI SM Filed Aug. 5, 1963 INVENTOR. I

lb 5 KENNETH L. VOUK FIG. I 3b fi h United States Patent 3,199,938 LATCH MEQHANISM Kenneth L. Vouk, Willowick, Ohio, assignor to Bailey Meter Company, a corporation of Delaware Filed Aug. 5, 1963, Ser. No. 299,785 2 Claims. (Cl. 312-333) My invention relates to a latch mechanism for releasably holding an electronic module in a mounting rack or panel.

Many latch mechanisms require special tools to ef- I fectuate release of the latched device. This often causes inconvenience as special tools are easily misplaced and the latched device cannot be released. Other latch mechanisms in addition to. special tools require the use of handles to extract the latched object after it is released.

The latch mechanism 1 have perfected is released from its locking position by merely pushing a button. Handles or other extracting means are not required as an ejection spring is employed to forcibly eject the latched device. Not only does the ejection spring forcibly eject, it also prevents relocking of the latch. No tools are required to release or latch the object.

To insure positive latching and prevent accidental release two latch mechanisms may preferably be employed. Under this arrangement, releasing one latch does not immediately release the latched object. With the two latched mechanism arrangement, one button is pushed and its associated latch is thereby released. Relocking of this latch is prevented by the forward off-center directed force of the ejection spring. Pushing the second button releases the second latch from its locking position. Again, the ejection spring prevents relocking of this latch. Since both latches are now released, the latched device is forcibly ejected. No pull-out handles are required because of the ejection spring action.

It is an object of my invention to provide a latch mechanism with positive snap action and a simple release mechanism.

It is a further object of my invention to provide a dual-latch mechanism to prevent accidental release.

Various other objects and advantages will be apparent from the following description of the invention. The novel features will be particularly pointed out in the appended claims.

My invention will be best understood by reference to the following detailed description and to the accompanying drawings in which:

FIG. 1 is an exploded view of a latch mechanism.

FIG. 2 is an isometric view showing an electronic module locked in the home position in a mounting rack by dual-latch mechanisms.

FIG. 3 is a detailed view, partially in cross section, of the latch mechanism shown in FIG. 1, in its locking position.

Referring now to FIGS. 1 and 3, there is shown a bell crank 1 having angularly disposed fingers 1a and 1b. The bell crank 1 is adapted to be rotatably mounted in a slotted base 6 by means of a pivot 2. When in the assembled condition, the finger 1b passes through a slot 3b in a plunger 3 and is confined therein by means of a pin 4. A coiled compression spring 7 encircles the plunger 3 and is held between a shoulder 5 on a cylindrical section 6a of the base 6 and pushbutton 3a formed on plunger 3. The bell crank 1 is thus normally urged in a clockwise direction until finger 1b engages the rear wall of cylindrical section 6a. Pushing pushbutton 3a against the action of spring 7 causes bell crank 1 to be rotated between limits in a counter-clockwise direction.

It will be apparent from inspection of FIG. 3 that such counter-clockwise positioning of finger in will cause 3,199,938 Patented Aug. 10, 1965 the tip thereof to ride past a properly located lip, such as shown at 15 of a stationary member 16, allowing movement to the right, as shown in the figure, of the latch mechanism and the device upon which it is mounted.

Referring now to FIG. 2 there is shown a typical application of the latch mechanism I have described with reference to FIGS. 1 and 3. In FIG. 2, I show a rectangular frame 9 for shrouding an electronic unit such as a printed circuit board. The frame 9, as shown, is in the home position in a mounting rack or panel 12 having a front opening 13 through which the frame 9 may be inserted or withdrawn. The mounting rack 12 is provided with rails 14 for guiding the frame 9 to or from the home position. Mounted on the rear wall of the rack 12 is an ejection spring 10 having parallel spaced apart leaf springs 10a and 10b urging the frame member forward, away from the home position. The leaf springs 10a and 10b are equally spaced and on opposite sides of a vertical plane passing through the horizontal center line of frame 9.

Latched mechanisms 8a and 8b, similar to the latch mechanism described with reference to FIGS. 1 and 3, are mounted on a front panel 911 of the frame 9. The tips of fingers 1a of latch mechanism 8a and 8b engage the rear surface of lips 11a and 11b respectively projecting into the front opening 13 in rack 12 when frame 9 is in the home position.

When it is desired to withdraw the frame 9 from rack 12 for repair or inspection of the housed module, the pushbutton 3a of latch 8a or of 8b is first pushed. Assuming pushbutton 3a of latch 8a is pushed, finger 1a will then disengage the rear surface of lip 11a and spring 10a will cause frame 9 to slightly cock in rails 14 sufficient to allow the tip of finger 1a to ride past lip 11a. When pushbutton 3a of latch 8b is then pushed, the as sociated tip 1a will ride past lip 11b. Leaf springs 10a and 10b will then move frame 9 forward along rails 14 away from the home position partially ejecting the frame 9 from rack 12. The removal may be completed by manually pulling the frame 9 forwardly until clear of the rack 12.

To insert frame 9 in rack 12 and properly locate in the home position, it is only necessary to manually push the rack along rails 14 until the tips of fingers 1a of latches 8a and 8b engage the rear surfaces of lips 11a and 11b, thus firmly locking the frame 9 in the home position.

While only one embodiment of the invention has been shown and rescribed, it will be apparent that many changes may be made in the construction and arrangement of parts without departing from the scope of the invention as defined in the following claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Apparatus for releasably holding a frame in a home position on a mounting rack or panel, said frame having a front, back, top and bottom of generally rectangular configuration forming a box-like member; said mounting rack having a front opening through which the frame may be inserted or withdrawn and a pair of horizontal rails for supporting and guiding said frame to the home position, a pair of spaced apart leaf springs mounted on the rear wall of said rack engaging the back of said frame on either side of its vertical center line when said frame is in the home position and independently urging the frame forwardly out of the home position toward said front opening, a lip formed on each of the two vertical edges of the front opening in said rack and two independently acting latch release mechanisms mounted on the front of said frame each engaging a separate one of said lips to lock said frame in the home position against the action of said springs and permitting said springs to move said frame forwardly when released out of engagementwith said lips.

2. Apparatus for releasably holding a frame, housing an electronic unit in a home position on a mounting rack or panel, said frame having a front, back, top 'and bottom of generally rectangular configuration forming a box-like member; said mounting rack having a front opening through which the frame may be inserted or withdrawn and a pair of horizontal rails for supporting and guiding said frame to the home position, the combination comprising: a pair of spaced apart leaf springs mounted onthe rear wall of said rack engaging the back of said frame on either side of its vertical center line when said frame is in its home position and independently urging the frame forwardly out of the home position toward said front opening; a lip formed on each of the two vertical edges of the front opening in said rack; a first rotatably mounted bell crank having a finger engaging the inward side of one lip on said rack when the frame is in its home position; a first spring release pushbutton 20 mounted on said frame for rotating the finger tip out of engagement with the inner side of said lip, said finger 'being held in its disengagementposition by one of said leaf springs; a second rotatably mounted bell crank having a finger engaging the inward side of one lip of said rack when the frame is in its home position; and a second spring release pushbutton mounted on said frame for rotating the-finger tip of said. second bell crank out of engagement with the inner side" of said 'lip, said finger being held in its disengagement position 'by the second of said leaf springs.

References Cited by the Examiner I UNITED STATES PATENTS FRANK B. SHERRY, Primary Examiner.

CHANCELLOR E. HARRIS, Examiner. 

1. APPARATUS FOR RELEASABLY HOLDING A FRAME IN A HOME POSITION ON A MOUNTING RACK OR PANEL, SAID FRAME HAVING A FRONT, BACK, TOP AND BOTTOM OF GENERALLY RECTANGULAR CONFIGURATION FORMING A BOX-LIKE MEMBER; SAID MOUNTING RACK HAVING A FRONT OPENING THROUGH WHICH THE FRAME MAY BE INSERTED OR WITHDRAWN AND A PAIR OF HORIZONTAL RAILS FOR SUPPORTING AND GUIDING SAID FRAME TO THE HOME POSITION, A PAIR OF SPACED APART LEAF SPRINGS MOUNTED ON THE REAR WALL OF SAID ENGAGING THE BACK OF SAID FRAME ON EITHER SIDE OF ITS VERTICAL CENTER LINE WHEN SAID FRAME IS IN THE HOME POSITION AND INDEPENDENTLY URGING THE 